//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the Owen Anderson and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements an analysis that determines, for a given memory
// operation, what preceding memory operations it depends on. It builds on
-// alias analysis information, and tries to provide a lazy, caching interface to
+// alias analysis information, and tries to provide a lazy, caching interface to
// a common kind of alias information query.
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "memdep"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Function.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetData.h"
-
using namespace llvm;
+STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
+STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
+STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
+
+STATISTIC(NumCacheNonLocalPtr,
+ "Number of fully cached non-local ptr responses");
+STATISTIC(NumCacheDirtyNonLocalPtr,
+ "Number of cached, but dirty, non-local ptr responses");
+STATISTIC(NumUncacheNonLocalPtr,
+ "Number of uncached non-local ptr responses");
+
char MemoryDependenceAnalysis::ID = 0;
-Instruction* MemoryDependenceAnalysis::NonLocal = (Instruction*)0;
-Instruction* MemoryDependenceAnalysis::None = (Instruction*)~0;
-
// Register this pass...
static RegisterPass<MemoryDependenceAnalysis> X("memdep",
- "Memory Dependence Analysis");
+ "Memory Dependence Analysis", false, true);
/// getAnalysisUsage - Does not modify anything. It uses Alias Analysis.
///
AU.addRequiredTransitive<TargetData>();
}
-// Find the dependency of a CallSite
-Instruction* MemoryDependenceAnalysis::getCallSiteDependency(CallSite C, bool local) {
- assert(local && "Non-local memory dependence analysis not yet implemented");
-
- AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
- TargetData& TD = getAnalysis<TargetData>();
- BasicBlock::iterator blockBegin = C.getInstruction()->getParent()->begin();
- BasicBlock::iterator QI = C.getInstruction();
-
- while (QI != blockBegin) {
- --QI;
+bool MemoryDependenceAnalysis::runOnFunction(Function &) {
+ AA = &getAnalysis<AliasAnalysis>();
+ TD = &getAnalysis<TargetData>();
+ return false;
+}
+
+
+/// getCallSiteDependencyFrom - Private helper for finding the local
+/// dependencies of a call site.
+MemDepResult MemoryDependenceAnalysis::
+getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt,
+ BasicBlock *BB) {
+ // Walk backwards through the block, looking for dependencies
+ while (ScanIt != BB->begin()) {
+ Instruction *Inst = --ScanIt;
// If this inst is a memory op, get the pointer it accessed
- Value* pointer = 0;
- uint64_t pointerSize = 0;
- if (StoreInst* S = dyn_cast<StoreInst>(QI)) {
- pointer = S->getPointerOperand();
- pointerSize = TD.getTypeSize(S->getOperand(0)->getType());
- } else if (LoadInst* L = dyn_cast<LoadInst>(QI)) {
- pointer = L->getPointerOperand();
- pointerSize = TD.getTypeSize(L->getType());
- } else if (AllocationInst* AI = dyn_cast<AllocationInst>(QI)) {
- pointer = AI;
- if (ConstantInt* C = dyn_cast<ConstantInt>(AI->getArraySize()))
- pointerSize = C->getZExtValue() * TD.getTypeSize(AI->getAllocatedType());
- else
- pointerSize = ~0UL;
- } else if (VAArgInst* V = dyn_cast<VAArgInst>(QI)) {
- pointer = V->getOperand(0);
- pointerSize = TD.getTypeSize(V->getType());
- } else if (FreeInst* F = dyn_cast<FreeInst>(QI)) {
- pointer = F->getPointerOperand();
+ Value *Pointer = 0;
+ uint64_t PointerSize = 0;
+ if (StoreInst *S = dyn_cast<StoreInst>(Inst)) {
+ Pointer = S->getPointerOperand();
+ PointerSize = TD->getTypeStoreSize(S->getOperand(0)->getType());
+ } else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
+ Pointer = V->getOperand(0);
+ PointerSize = TD->getTypeStoreSize(V->getType());
+ } else if (FreeInst *F = dyn_cast<FreeInst>(Inst)) {
+ Pointer = F->getPointerOperand();
// FreeInsts erase the entire structure
- pointerSize = ~0UL;
- } else if (CallSite::get(QI).getInstruction() != 0) {
- if (AA.getModRefInfo(C, CallSite::get(QI)) != AliasAnalysis::NoModRef) {
- depGraphLocal.insert(std::make_pair(C.getInstruction(), std::make_pair(QI, true)));
- reverseDep.insert(std::make_pair(QI, C.getInstruction()));
- return QI;
- } else {
+ PointerSize = ~0ULL;
+ } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
+ CallSite InstCS = CallSite::get(Inst);
+ // If these two calls do not interfere, look past it.
+ if (AA->getModRefInfo(CS, InstCS) == AliasAnalysis::NoModRef)
continue;
- }
- } else
+
+ // FIXME: If this is a ref/ref result, we should ignore it!
+ // X = strlen(P);
+ // Y = strlen(Q);
+ // Z = strlen(P); // Z = X
+
+ // If they interfere, we generally return clobber. However, if they are
+ // calls to the same read-only functions we return Def.
+ if (!AA->onlyReadsMemory(CS) || CS.getCalledFunction() == 0 ||
+ CS.getCalledFunction() != InstCS.getCalledFunction())
+ return MemDepResult::getClobber(Inst);
+ return MemDepResult::getDef(Inst);
+ } else {
+ // Non-memory instruction.
continue;
+ }
+
+ if (AA->getModRefInfo(CS, Pointer, PointerSize) != AliasAnalysis::NoModRef)
+ return MemDepResult::getClobber(Inst);
+ }
+
+ // No dependence found. If this is the entry block of the function, it is a
+ // clobber, otherwise it is non-local.
+ if (BB != &BB->getParent()->getEntryBlock())
+ return MemDepResult::getNonLocal();
+ return MemDepResult::getClobber(ScanIt);
+}
+
+/// getPointerDependencyFrom - Return the instruction on which a memory
+/// location depends. If isLoad is true, this routine ignore may-aliases with
+/// read-only operations.
+MemDepResult MemoryDependenceAnalysis::
+getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
+ BasicBlock::iterator ScanIt, BasicBlock *BB) {
+
+ // Walk backwards through the basic block, looking for dependencies.
+ while (ScanIt != BB->begin()) {
+ Instruction *Inst = --ScanIt;
+
+ // Values depend on loads if the pointers are must aliased. This means that
+ // a load depends on another must aliased load from the same value.
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ Value *Pointer = LI->getPointerOperand();
+ uint64_t PointerSize = TD->getTypeStoreSize(LI->getType());
+
+ // If we found a pointer, check if it could be the same as our pointer.
+ AliasAnalysis::AliasResult R =
+ AA->alias(Pointer, PointerSize, MemPtr, MemSize);
+ if (R == AliasAnalysis::NoAlias)
+ continue;
+
+ // May-alias loads don't depend on each other without a dependence.
+ if (isLoad && R == AliasAnalysis::MayAlias)
+ continue;
+ // Stores depend on may and must aliased loads, loads depend on must-alias
+ // loads.
+ return MemDepResult::getDef(Inst);
+ }
- if (AA.getModRefInfo(C, pointer, pointerSize) != AliasAnalysis::NoModRef) {
- depGraphLocal.insert(std::make_pair(C.getInstruction(), std::make_pair(QI, true)));
- reverseDep.insert(std::make_pair(QI, C.getInstruction()));
- return QI;
+ if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ Value *Pointer = SI->getPointerOperand();
+ uint64_t PointerSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
+
+ // If we found a pointer, check if it could be the same as our pointer.
+ AliasAnalysis::AliasResult R =
+ AA->alias(Pointer, PointerSize, MemPtr, MemSize);
+
+ if (R == AliasAnalysis::NoAlias)
+ continue;
+ if (R == AliasAnalysis::MayAlias)
+ return MemDepResult::getClobber(Inst);
+ return MemDepResult::getDef(Inst);
+ }
+
+ // If this is an allocation, and if we know that the accessed pointer is to
+ // the allocation, return Def. This means that there is no dependence and
+ // the access can be optimized based on that. For example, a load could
+ // turn into undef.
+ if (AllocationInst *AI = dyn_cast<AllocationInst>(Inst)) {
+ Value *AccessPtr = MemPtr->getUnderlyingObject();
+
+ if (AccessPtr == AI ||
+ AA->alias(AI, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
+ return MemDepResult::getDef(AI);
+ continue;
}
+
+ // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
+ // FIXME: If this is a load, we should ignore readonly calls!
+ if (AA->getModRefInfo(Inst, MemPtr, MemSize) == AliasAnalysis::NoModRef)
+ continue;
+
+ // Otherwise, there is a dependence.
+ return MemDepResult::getClobber(Inst);
}
- // No dependence found
- depGraphLocal.insert(std::make_pair(C.getInstruction(), std::make_pair(NonLocal, true)));
- reverseDep.insert(std::make_pair(NonLocal, C.getInstruction()));
- return NonLocal;
+ // No dependence found. If this is the entry block of the function, it is a
+ // clobber, otherwise it is non-local.
+ if (BB != &BB->getParent()->getEntryBlock())
+ return MemDepResult::getNonLocal();
+ return MemDepResult::getClobber(ScanIt);
}
/// getDependency - Return the instruction on which a memory operation
-/// depends. The local paramter indicates if the query should only
-/// evaluate dependencies within the same basic block.
-Instruction* MemoryDependenceAnalysis::getDependency(Instruction* query,
- bool local) {
- if (!local)
- assert(0 && "Non-local memory dependence is not yet supported.");
-
- // Start looking for dependencies with the queried inst
- BasicBlock::iterator QI = query;
+/// depends.
+MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
+ Instruction *ScanPos = QueryInst;
// Check for a cached result
- std::pair<Instruction*, bool> cachedResult = depGraphLocal[query];
- // If we have a _confirmed_ cached entry, return it
- if (cachedResult.second)
- return cachedResult.first;
- else if (cachedResult.first != NonLocal)
- // If we have an unconfirmed cached entry, we can start our search from there
- QI = cachedResult.first;
-
- AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
- TargetData& TD = getAnalysis<TargetData>();
-
- // Get the pointer value for which dependence will be determined
- Value* dependee = 0;
- uint64_t dependeeSize = 0;
- bool queryIsVolatile = false;
- if (StoreInst* S = dyn_cast<StoreInst>(QI)) {
- dependee = S->getPointerOperand();
- dependeeSize = TD.getTypeSize(S->getOperand(0)->getType());
- queryIsVolatile = S->isVolatile();
- } else if (LoadInst* L = dyn_cast<LoadInst>(QI)) {
- dependee = L->getPointerOperand();
- dependeeSize = TD.getTypeSize(L->getType());
- queryIsVolatile = L->isVolatile();
- } else if (VAArgInst* V = dyn_cast<VAArgInst>(QI)) {
- dependee = V->getOperand(0);
- dependeeSize = TD.getTypeSize(V->getType());
- } else if (FreeInst* F = dyn_cast<FreeInst>(QI)) {
- dependee = F->getPointerOperand();
-
- // FreeInsts erase the entire structure, not just a field
- dependeeSize = ~0UL;
- } else if (CallSite::get(QI).getInstruction() != 0)
- return getCallSiteDependency(CallSite::get(QI));
- else if (isa<AllocationInst>(query))
- return None;
- else
- return None;
-
- BasicBlock::iterator blockBegin = query->getParent()->begin();
-
- while (QI != blockBegin) {
- --QI;
+ MemDepResult &LocalCache = LocalDeps[QueryInst];
+
+ // If the cached entry is non-dirty, just return it. Note that this depends
+ // on MemDepResult's default constructing to 'dirty'.
+ if (!LocalCache.isDirty())
+ return LocalCache;
- // If this inst is a memory op, get the pointer it accessed
- Value* pointer = 0;
- uint64_t pointerSize = 0;
- if (StoreInst* S = dyn_cast<StoreInst>(QI)) {
- // All volatile loads/stores depend on each other
- if (queryIsVolatile && S->isVolatile()) {
- depGraphLocal.insert(std::make_pair(query, std::make_pair(S, true)));
- reverseDep.insert(std::make_pair(S, query));
- return S;
- }
+ // Otherwise, if we have a dirty entry, we know we can start the scan at that
+ // instruction, which may save us some work.
+ if (Instruction *Inst = LocalCache.getInst()) {
+ ScanPos = Inst;
+
+ SmallPtrSet<Instruction*, 4> &InstMap = ReverseLocalDeps[Inst];
+ bool Found = InstMap.erase(QueryInst);
+ assert(Found && "Invalid reverse map!"); Found=Found;
+ if (InstMap.empty())
+ // FIXME: use an iterator to avoid looking up inst again.
+ ReverseLocalDeps.erase(Inst);
+ }
+
+ BasicBlock *QueryParent = QueryInst->getParent();
+
+ Value *MemPtr = 0;
+ uint64_t MemSize = 0;
+
+ // Do the scan.
+ if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
+ // No dependence found. If this is the entry block of the function, it is a
+ // clobber, otherwise it is non-local.
+ if (QueryParent != &QueryParent->getParent()->getEntryBlock())
+ LocalCache = MemDepResult::getNonLocal();
+ else
+ LocalCache = MemDepResult::getClobber(QueryInst);
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
+ // If this is a volatile store, don't mess around with it. Just return the
+ // previous instruction as a clobber.
+ if (SI->isVolatile())
+ LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
+ else {
+ MemPtr = SI->getPointerOperand();
+ MemSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
+ }
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
+ // If this is a volatile load, don't mess around with it. Just return the
+ // previous instruction as a clobber.
+ if (LI->isVolatile())
+ LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
+ else {
+ MemPtr = LI->getPointerOperand();
+ MemSize = TD->getTypeStoreSize(LI->getType());
+ }
+ } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
+ LocalCache = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
+ QueryParent);
+ } else if (FreeInst *FI = dyn_cast<FreeInst>(QueryInst)) {
+ MemPtr = FI->getPointerOperand();
+ // FreeInsts erase the entire structure, not just a field.
+ MemSize = ~0UL;
+ } else {
+ // Non-memory instruction.
+ LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
+ }
+
+ // If we need to do a pointer scan, make it happen.
+ if (MemPtr)
+ LocalCache = getPointerDependencyFrom(MemPtr, MemSize,
+ isa<LoadInst>(QueryInst),
+ ScanPos, QueryParent);
+
+ // Remember the result!
+ if (Instruction *I = LocalCache.getInst())
+ ReverseLocalDeps[I].insert(QueryInst);
+
+ return LocalCache;
+}
+
+/// getNonLocalDependency - Perform a full dependency query for the
+/// specified instruction, returning the set of blocks that the value is
+/// potentially live across. The returned set of results will include a
+/// "NonLocal" result for all blocks where the value is live across.
+///
+/// This method assumes the instruction returns a "nonlocal" dependency
+/// within its own block.
+///
+const MemoryDependenceAnalysis::NonLocalDepInfo &
+MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst) {
+ // FIXME: Make this only be for callsites in the future.
+ assert(isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst) ||
+ isa<LoadInst>(QueryInst) || isa<StoreInst>(QueryInst));
+ assert(getDependency(QueryInst).isNonLocal() &&
+ "getNonLocalDependency should only be used on insts with non-local deps!");
+ PerInstNLInfo &CacheP = NonLocalDeps[QueryInst];
+ NonLocalDepInfo &Cache = CacheP.first;
+
+ /// DirtyBlocks - This is the set of blocks that need to be recomputed. In
+ /// the cached case, this can happen due to instructions being deleted etc. In
+ /// the uncached case, this starts out as the set of predecessors we care
+ /// about.
+ SmallVector<BasicBlock*, 32> DirtyBlocks;
+
+ if (!Cache.empty()) {
+ // Okay, we have a cache entry. If we know it is not dirty, just return it
+ // with no computation.
+ if (!CacheP.second) {
+ NumCacheNonLocal++;
+ return Cache;
+ }
+
+ // If we already have a partially computed set of results, scan them to
+ // determine what is dirty, seeding our initial DirtyBlocks worklist.
+ for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
+ I != E; ++I)
+ if (I->second.isDirty())
+ DirtyBlocks.push_back(I->first);
+
+ // Sort the cache so that we can do fast binary search lookups below.
+ std::sort(Cache.begin(), Cache.end());
+
+ ++NumCacheDirtyNonLocal;
+ //cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
+ // << Cache.size() << " cached: " << *QueryInst;
+ } else {
+ // Seed DirtyBlocks with each of the preds of QueryInst's block.
+ BasicBlock *QueryBB = QueryInst->getParent();
+ DirtyBlocks.append(pred_begin(QueryBB), pred_end(QueryBB));
+ NumUncacheNonLocal++;
+ }
+
+ // Visited checked first, vector in sorted order.
+ SmallPtrSet<BasicBlock*, 64> Visited;
+
+ unsigned NumSortedEntries = Cache.size();
+
+ // Iterate while we still have blocks to update.
+ while (!DirtyBlocks.empty()) {
+ BasicBlock *DirtyBB = DirtyBlocks.back();
+ DirtyBlocks.pop_back();
+
+ // Already processed this block?
+ if (!Visited.insert(DirtyBB))
+ continue;
+
+ // Do a binary search to see if we already have an entry for this block in
+ // the cache set. If so, find it.
+ NonLocalDepInfo::iterator Entry =
+ std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
+ std::make_pair(DirtyBB, MemDepResult()));
+ if (Entry != Cache.begin() && (&*Entry)[-1].first == DirtyBB)
+ --Entry;
+
+ MemDepResult *ExistingResult = 0;
+ if (Entry != Cache.begin()+NumSortedEntries &&
+ Entry->first == DirtyBB) {
+ // If we already have an entry, and if it isn't already dirty, the block
+ // is done.
+ if (!Entry->second.isDirty())
+ continue;
- pointer = S->getPointerOperand();
- pointerSize = TD.getTypeSize(S->getOperand(0)->getType());
- } else if (LoadInst* L = dyn_cast<LoadInst>(QI)) {
- // All volatile loads/stores depend on each other
- if (queryIsVolatile && L->isVolatile()) {
- depGraphLocal.insert(std::make_pair(query, std::make_pair(L, true)));
- reverseDep.insert(std::make_pair(L, query));
- return L;
- }
+ // Otherwise, remember this slot so we can update the value.
+ ExistingResult = &Entry->second;
+ }
+
+ // If the dirty entry has a pointer, start scanning from it so we don't have
+ // to rescan the entire block.
+ BasicBlock::iterator ScanPos = DirtyBB->end();
+ if (ExistingResult) {
+ if (Instruction *Inst = ExistingResult->getInst()) {
+ ScanPos = Inst;
- pointer = L->getPointerOperand();
- pointerSize = TD.getTypeSize(L->getType());
- } else if (AllocationInst* AI = dyn_cast<AllocationInst>(QI)) {
- pointer = AI;
- if (ConstantInt* C = dyn_cast<ConstantInt>(AI->getArraySize()))
- pointerSize = C->getZExtValue() * TD.getTypeSize(AI->getAllocatedType());
+ // We're removing QueryInst's use of Inst.
+ SmallPtrSet<Instruction*, 4> &InstMap = ReverseNonLocalDeps[Inst];
+ bool Found = InstMap.erase(QueryInst);
+ assert(Found && "Invalid reverse map!"); Found=Found;
+ // FIXME: Use an iterator to avoid looking up inst again.
+ if (InstMap.empty()) ReverseNonLocalDeps.erase(Inst);
+ }
+ }
+
+ // Find out if this block has a local dependency for QueryInst.
+ MemDepResult Dep;
+
+ Value *MemPtr = 0;
+ uint64_t MemSize = 0;
+
+ if (ScanPos == DirtyBB->begin()) {
+ // No dependence found. If this is the entry block of the function, it is a
+ // clobber, otherwise it is non-local.
+ if (DirtyBB != &DirtyBB->getParent()->getEntryBlock())
+ Dep = MemDepResult::getNonLocal();
else
- pointerSize = ~0UL;
- } else if (VAArgInst* V = dyn_cast<VAArgInst>(QI)) {
- pointer = V->getOperand(0);
- pointerSize = TD.getTypeSize(V->getType());
- } else if (FreeInst* F = dyn_cast<FreeInst>(QI)) {
- pointer = F->getPointerOperand();
-
- // FreeInsts erase the entire structure
- pointerSize = ~0UL;
- } else if (CallSite::get(QI).getInstruction() != 0) {
- // Call insts need special handling. Check is they can modify our pointer
- if (AA.getModRefInfo(CallSite::get(QI), dependee, dependeeSize) !=
- AliasAnalysis::NoModRef) {
- depGraphLocal.insert(std::make_pair(query, std::make_pair(QI, true)));
- reverseDep.insert(std::make_pair(QI, query));
- return QI;
- } else {
- continue;
+ Dep = MemDepResult::getClobber(ScanPos);
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
+ // If this is a volatile store, don't mess around with it. Just return the
+ // previous instruction as a clobber.
+ if (SI->isVolatile())
+ Dep = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
+ else {
+ MemPtr = SI->getPointerOperand();
+ MemSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
+ }
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
+ // If this is a volatile load, don't mess around with it. Just return the
+ // previous instruction as a clobber.
+ if (LI->isVolatile())
+ Dep = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
+ else {
+ MemPtr = LI->getPointerOperand();
+ MemSize = TD->getTypeStoreSize(LI->getType());
}
+ } else {
+ assert(isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst));
+ Dep = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
+ DirtyBB);
}
- // If we found a pointer, check if it could be the same as our pointer
- if (pointer) {
- AliasAnalysis::AliasResult R = AA.alias(pointer, pointerSize,
- dependee, dependeeSize);
+ if (MemPtr)
+ Dep = getPointerDependencyFrom(MemPtr, MemSize, isa<LoadInst>(QueryInst),
+ ScanPos, DirtyBB);
+
+ // If we had a dirty entry for the block, update it. Otherwise, just add
+ // a new entry.
+ if (ExistingResult)
+ *ExistingResult = Dep;
+ else
+ Cache.push_back(std::make_pair(DirtyBB, Dep));
+
+ // If the block has a dependency (i.e. it isn't completely transparent to
+ // the value), remember the association!
+ if (!Dep.isNonLocal()) {
+ // Keep the ReverseNonLocalDeps map up to date so we can efficiently
+ // update this when we remove instructions.
+ if (Instruction *Inst = Dep.getInst())
+ ReverseNonLocalDeps[Inst].insert(QueryInst);
+ } else {
+
+ // If the block *is* completely transparent to the load, we need to check
+ // the predecessors of this block. Add them to our worklist.
+ DirtyBlocks.append(pred_begin(DirtyBB), pred_end(DirtyBB));
+ }
+ }
+
+ return Cache;
+}
+
+/// getNonLocalPointerDependency - Perform a full dependency query for an
+/// access to the specified (non-volatile) memory location, returning the
+/// set of instructions that either define or clobber the value.
+///
+/// This method assumes the pointer has a "NonLocal" dependency within its
+/// own block.
+///
+void MemoryDependenceAnalysis::
+getNonLocalPointerDependency(Value *Pointer, bool isLoad, BasicBlock *FromBB,
+ SmallVectorImpl<NonLocalDepEntry> &Result) {
+ Result.clear();
+
+ // We know that the pointer value is live into FromBB find the def/clobbers
+ // from presecessors.
+ const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
+ uint64_t PointeeSize = TD->getTypeStoreSize(EltTy);
+
+ // While we have blocks to analyze, get their values.
+ SmallPtrSet<BasicBlock*, 64> Visited;
+
+ for (pred_iterator PI = pred_begin(FromBB), E = pred_end(FromBB); PI != E;
+ ++PI) {
+ // TODO: PHI TRANSLATE.
+ getNonLocalPointerDepInternal(Pointer, PointeeSize, isLoad, *PI,
+ Result, Visited);
+ }
+}
+
+void MemoryDependenceAnalysis::
+getNonLocalPointerDepInternal(Value *Pointer, uint64_t PointeeSize,
+ bool isLoad, BasicBlock *StartBB,
+ SmallVectorImpl<NonLocalDepEntry> &Result,
+ SmallPtrSet<BasicBlock*, 64> &Visited) {
+ SmallVector<BasicBlock*, 32> Worklist;
+ Worklist.push_back(StartBB);
+
+ // Look up the cached info for Pointer.
+ ValueIsLoadPair CacheKey(Pointer, isLoad);
+ NonLocalDepInfo *Cache = &NonLocalPointerDeps[CacheKey];
+
+ // Keep track of the entries that we know are sorted. Previously cached
+ // entries will all be sorted. The entries we add we only sort on demand (we
+ // don't insert every element into its sorted position). We know that we
+ // won't get any reuse from currently inserted values, because we don't
+ // revisit blocks after we insert info for them.
+ unsigned NumSortedEntries = Cache->size();
+
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.pop_back_val();
+
+ // Analyze the dependency of *Pointer in FromBB. See if we already have
+ // been here.
+ if (!Visited.insert(BB))
+ continue;
+
+ // Get the dependency info for Pointer in BB. If we have cached
+ // information, we will use it, otherwise we compute it.
+
+ // Do a binary search to see if we already have an entry for this block in
+ // the cache set. If so, find it.
+ NonLocalDepInfo::iterator Entry =
+ std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries,
+ std::make_pair(BB, MemDepResult()));
+ if (Entry != Cache->begin() && (&*Entry)[-1].first == BB)
+ --Entry;
+
+ MemDepResult *ExistingResult = 0;
+ if (Entry != Cache->begin()+NumSortedEntries && Entry->first == BB)
+ ExistingResult = &Entry->second;
+
+ // If we have a cached entry, and it is non-dirty, use it as the value for
+ // this dependency.
+ MemDepResult Dep;
+ if (ExistingResult && !ExistingResult->isDirty()) {
+ Dep = *ExistingResult;
+ ++NumCacheNonLocalPtr;
+ } else {
+ // Otherwise, we have to scan for the value. If we have a dirty cache
+ // entry, start scanning from its position, otherwise we scan from the end
+ // of the block.
+ BasicBlock::iterator ScanPos = BB->end();
+ if (ExistingResult && ExistingResult->getInst()) {
+ assert(ExistingResult->getInst()->getParent() == BB &&
+ "Instruction invalidated?");
+ ++NumCacheDirtyNonLocalPtr;
+ ScanPos = ExistingResult->getInst();
+
+ // Eliminating the dirty entry from 'Cache', so update the reverse info.
+ SmallPtrSet<void *, 4> &InstMap = ReverseNonLocalPtrDeps[ScanPos];
+ bool Contained = InstMap.erase(CacheKey.getOpaqueValue());
+ assert(Contained && "Invalid cache entry"); Contained=Contained;
+ // FIXME: Use an iterator to avoid a repeated lookup in ".erase".
+ if (InstMap.empty()) ReverseNonLocalPtrDeps.erase(ScanPos);
+ } else {
+ ++NumUncacheNonLocalPtr;
+ }
+
+ // Scan the block for the dependency.
+ Dep = getPointerDependencyFrom(Pointer, PointeeSize, isLoad, ScanPos, BB);
- if (R != AliasAnalysis::NoAlias) {
- depGraphLocal.insert(std::make_pair(query, std::make_pair(QI, true)));
- reverseDep.insert(std::make_pair(QI, query));
- return QI;
+ // If we had a dirty entry for the block, update it. Otherwise, just add
+ // a new entry.
+ if (ExistingResult)
+ *ExistingResult = Dep;
+ else
+ Cache->push_back(std::make_pair(BB, Dep));
+
+ // If the block has a dependency (i.e. it isn't completely transparent to
+ // the value), remember the reverse association because we just added it
+ // to Cache!
+ if (!Dep.isNonLocal()) {
+ // Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
+ // update MemDep when we remove instructions.
+ Instruction *Inst = Dep.getInst();
+ assert(Inst && "Didn't depend on anything?");
+ ReverseNonLocalPtrDeps[Inst].insert(CacheKey.getOpaqueValue());
}
}
+
+ // If we got a Def or Clobber, add this to the list of results.
+ if (!Dep.isNonLocal()) {
+ Result.push_back(NonLocalDepEntry(BB, Dep));
+ continue;
+ }
+
+ // Otherwise, we have to process all the predecessors of this block to scan
+ // them as well.
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
+ // TODO: PHI TRANSLATE.
+ Worklist.push_back(*PI);
+ }
}
- // If we found nothing, return the non-local flag
- depGraphLocal.insert(std::make_pair(query,
- std::make_pair(NonLocal, true)));
- reverseDep.insert(std::make_pair(NonLocal, query));
+ // If we computed new values, re-sort Cache.
+ if (NumSortedEntries != Cache->size())
+ std::sort(Cache->begin(), Cache->end());
+}
+
+/// RemoveCachedNonLocalPointerDependencies - If P exists in
+/// CachedNonLocalPointerInfo, remove it.
+void MemoryDependenceAnalysis::
+RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) {
+ CachedNonLocalPointerInfo::iterator It =
+ NonLocalPointerDeps.find(P);
+ if (It == NonLocalPointerDeps.end()) return;
+
+ // Remove all of the entries in the BB->val map. This involves removing
+ // instructions from the reverse map.
+ NonLocalDepInfo &PInfo = It->second;
+
+ for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
+ Instruction *Target = PInfo[i].second.getInst();
+ if (Target == 0) continue; // Ignore non-local dep results.
+ assert(Target->getParent() == PInfo[i].first && Target != P.getPointer());
+
+ // Eliminating the dirty entry from 'Cache', so update the reverse info.
+ SmallPtrSet<void *, 4> &InstMap = ReverseNonLocalPtrDeps[Target];
+ bool Contained = InstMap.erase(P.getOpaqueValue());
+ assert(Contained && "Invalid cache entry"); Contained=Contained;
+
+ // FIXME: Use an iterator to avoid a repeated lookup in ".erase".
+ if (InstMap.empty()) ReverseNonLocalPtrDeps.erase(Target);
+ }
- return NonLocal;
+ // Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
+ NonLocalPointerDeps.erase(It);
}
+
/// removeInstruction - Remove an instruction from the dependence analysis,
/// updating the dependence of instructions that previously depended on it.
-void MemoryDependenceAnalysis::removeInstruction(Instruction* rem) {
- // Figure out the new dep for things that currently depend on rem
- Instruction* newDep = NonLocal;
- if (depGraphLocal[rem].first != NonLocal) {
- // If we have dep info for rem, set them to it
- BasicBlock::iterator RI = depGraphLocal[rem].first;
- RI++;
- newDep = RI;
- } else if (depGraphLocal[rem].first == NonLocal &&
- depGraphLocal[rem].second ) {
- // If we have a confirmed non-local flag, use it
- newDep = NonLocal;
- } else {
- // Otherwise, use the immediate successor of rem
- // NOTE: This is because, when getDependence is called, it will first check
- // the immediate predecessor of what is in the cache.
- BasicBlock::iterator RI = rem;
- RI++;
- newDep = RI;
+/// This method attempts to keep the cache coherent using the reverse map.
+void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
+ // Walk through the Non-local dependencies, removing this one as the value
+ // for any cached queries.
+ NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
+ if (NLDI != NonLocalDeps.end()) {
+ NonLocalDepInfo &BlockMap = NLDI->second.first;
+ for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
+ DI != DE; ++DI)
+ if (Instruction *Inst = DI->second.getInst())
+ ReverseNonLocalDeps[Inst].erase(RemInst);
+ NonLocalDeps.erase(NLDI);
+ }
+
+ // If we have a cached local dependence query for this instruction, remove it.
+ //
+ LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
+ if (LocalDepEntry != LocalDeps.end()) {
+ // Remove us from DepInst's reverse set now that the local dep info is gone.
+ if (Instruction *Inst = LocalDepEntry->second.getInst()) {
+ SmallPtrSet<Instruction*, 4> &RLD = ReverseLocalDeps[Inst];
+ bool Found = RLD.erase(RemInst);
+ assert(Found && "Invalid reverse map!"); Found=Found;
+ // FIXME: Use an iterator to avoid looking up Inst again.
+ if (RLD.empty())
+ ReverseLocalDeps.erase(Inst);
+ }
+
+ // Remove this local dependency info.
+ LocalDeps.erase(LocalDepEntry);
+ }
+
+ // If we have any cached pointer dependencies on this instruction, remove
+ // them. If the instruction has non-pointer type, then it can't be a pointer
+ // base.
+
+ // Remove it from both the load info and the store info. The instruction
+ // can't be in either of these maps if it is non-pointer.
+ if (isa<PointerType>(RemInst->getType())) {
+ RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
+ RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
}
+
+ // Loop over all of the things that depend on the instruction we're removing.
+ //
+ SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
+
+ ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
+ if (ReverseDepIt != ReverseLocalDeps.end()) {
+ SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
+ // RemInst can't be the terminator if it has local stuff depending on it.
+ assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
+ "Nothing can locally depend on a terminator");
+
+ // Anything that was locally dependent on RemInst is now going to be
+ // dependent on the instruction after RemInst. It will have the dirty flag
+ // set so it will rescan. This saves having to scan the entire block to get
+ // to this point.
+ Instruction *NewDepInst = ++BasicBlock::iterator(RemInst);
+
+ for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
+ E = ReverseDeps.end(); I != E; ++I) {
+ Instruction *InstDependingOnRemInst = *I;
+ assert(InstDependingOnRemInst != RemInst &&
+ "Already removed our local dep info");
+
+ LocalDeps[InstDependingOnRemInst] = MemDepResult::getDirty(NewDepInst);
+
+ // Make sure to remember that new things depend on NewDepInst.
+ ReverseDepsToAdd.push_back(std::make_pair(NewDepInst,
+ InstDependingOnRemInst));
+ }
+
+ ReverseLocalDeps.erase(ReverseDepIt);
- std::multimap<Instruction*, Instruction*>::iterator I = reverseDep.find(rem);
- while (I->first == rem) {
- // Insert the new dependencies
- // Mark it as unconfirmed as long as it is not the non-local flag
- depGraphLocal[I->second] = std::make_pair(newDep, !newDep);
- reverseDep.erase(I);
- I = reverseDep.find(rem);
+ // Add new reverse deps after scanning the set, to avoid invalidating the
+ // 'ReverseDeps' reference.
+ while (!ReverseDepsToAdd.empty()) {
+ ReverseLocalDeps[ReverseDepsToAdd.back().first]
+ .insert(ReverseDepsToAdd.back().second);
+ ReverseDepsToAdd.pop_back();
+ }
}
+
+ ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
+ if (ReverseDepIt != ReverseNonLocalDeps.end()) {
+ SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
+ for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
+ I != E; ++I) {
+ assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
+
+ PerInstNLInfo &INLD = NonLocalDeps[*I];
+ // The information is now dirty!
+ INLD.second = true;
+
+ for (NonLocalDepInfo::iterator DI = INLD.first.begin(),
+ DE = INLD.first.end(); DI != DE; ++DI) {
+ if (DI->second.getInst() != RemInst) continue;
+
+ // Convert to a dirty entry for the subsequent instruction.
+ Instruction *NextI = 0;
+ if (!RemInst->isTerminator()) {
+ NextI = ++BasicBlock::iterator(RemInst);
+ ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
+ }
+ DI->second = MemDepResult::getDirty(NextI);
+ }
+ }
+
+ ReverseNonLocalDeps.erase(ReverseDepIt);
+
+ // Add new reverse deps after scanning the set, to avoid invalidating 'Set'
+ while (!ReverseDepsToAdd.empty()) {
+ ReverseNonLocalDeps[ReverseDepsToAdd.back().first]
+ .insert(ReverseDepsToAdd.back().second);
+ ReverseDepsToAdd.pop_back();
+ }
+ }
+
+ // If the instruction is in ReverseNonLocalPtrDeps then it appears as a
+ // value in the NonLocalPointerDeps info.
+ ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
+ ReverseNonLocalPtrDeps.find(RemInst);
+ if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
+ SmallPtrSet<void*, 4> &Set = ReversePtrDepIt->second;
+ SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
+
+ for (SmallPtrSet<void*, 4>::iterator I = Set.begin(), E = Set.end();
+ I != E; ++I) {
+ ValueIsLoadPair P;
+ P.setFromOpaqueValue(*I);
+ assert(P.getPointer() != RemInst &&
+ "Already removed NonLocalPointerDeps info for RemInst");
+
+ NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P];
+
+ MemDepResult NewDirtyVal;
+ if (!RemInst->isTerminator())
+ NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst));
+
+ // Update any entries for RemInst to use the instruction after it.
+ for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
+ DI != DE; ++DI) {
+ if (DI->second.getInst() != RemInst) continue;
+
+ // Convert to a dirty entry for the subsequent instruction.
+ DI->second = NewDirtyVal;
+
+ if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
+ ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
+ }
+ }
+
+ ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
+
+ while (!ReversePtrDepsToAdd.empty()) {
+ ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
+ .insert(ReversePtrDepsToAdd.back().second.getOpaqueValue());
+ ReversePtrDepsToAdd.pop_back();
+ }
+ }
+
+
+ assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
+ AA->deleteValue(RemInst);
+ DEBUG(verifyRemoved(RemInst));
+}
+
+/// verifyRemoved - Verify that the specified instruction does not occur
+/// in our internal data structures.
+void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
+ for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
+ E = LocalDeps.end(); I != E; ++I) {
+ assert(I->first != D && "Inst occurs in data structures");
+ assert(I->second.getInst() != D &&
+ "Inst occurs in data structures");
+ }
+
+ for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(),
+ E = NonLocalPointerDeps.end(); I != E; ++I) {
+ assert(I->first.getPointer() != D && "Inst occurs in NLPD map key");
+ const NonLocalDepInfo &Val = I->second;
+ for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
+ II != E; ++II)
+ assert(II->second.getInst() != D && "Inst occurs as NLPD value");
+ }
+
+ for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
+ E = NonLocalDeps.end(); I != E; ++I) {
+ assert(I->first != D && "Inst occurs in data structures");
+ const PerInstNLInfo &INLD = I->second;
+ for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
+ EE = INLD.first.end(); II != EE; ++II)
+ assert(II->second.getInst() != D && "Inst occurs in data structures");
+ }
+
+ for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
+ E = ReverseLocalDeps.end(); I != E; ++I) {
+ assert(I->first != D && "Inst occurs in data structures");
+ for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
+ EE = I->second.end(); II != EE; ++II)
+ assert(*II != D && "Inst occurs in data structures");
+ }
+
+ for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
+ E = ReverseNonLocalDeps.end();
+ I != E; ++I) {
+ assert(I->first != D && "Inst occurs in data structures");
+ for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
+ EE = I->second.end(); II != EE; ++II)
+ assert(*II != D && "Inst occurs in data structures");
+ }
+
+ for (ReverseNonLocalPtrDepTy::const_iterator
+ I = ReverseNonLocalPtrDeps.begin(),
+ E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
+ assert(I->first != D && "Inst occurs in rev NLPD map");
+
+ for (SmallPtrSet<void*, 4>::const_iterator II = I->second.begin(),
+ E = I->second.end(); II != E; ++II)
+ assert(*II != ValueIsLoadPair(D, false).getOpaqueValue() &&
+ *II != ValueIsLoadPair(D, true).getOpaqueValue() &&
+ "Inst occurs in ReverseNonLocalPtrDeps map");
+ }
+
}
projects / oota-llvm.git / blobdiff